This invention relates to improvements in a production technique for high bearing pressure-resistant members such as discs and input and output power rollers used in a toroidal continuously variable transmission and gears, and more particularly to steels for the high bearing pressure-resistant members which steels are improved in machinability upon undergoing a heat treatment for spheroidizing and to high bearing pressure-resistant members formed of such steels.
It has been hitherto known that a machine structural steel containing 0.15 to 0.25% by weight of C, not less than 0.4% by weight of Si and 1 to 3% by weight of Ni is formed into a high bearing pressure-resistant member excellent in performance upon undergoing a surface hardening treatment such as carburizing or carbonitriding. In case of producing a high bearing pressure-resistant member by using such a machine structural steel, it is required to make a softening heat treatment on the machine structural steel prior to machining since the machinability of the machine structural steel as a raw material steel is very low upon hot working, in order to obtain objective shape and dimensions under machining.